Project Summary/Abstract The aim of this proposal is to develop a new generation of miniaturized implantable micro-stimulators suitable for chronic implantation in a patient's eye to treat degenerative diseases of the retina. In this study, we will use polyimide electrode array structures coated with inorganic materials to provide a long-lasting implant-tissue interface. Custom packaging and assembly methods for the prostheses will also be developed. The tasks to be accomplished under this proposal include the microfabrication of multi-layered electrode array structures in polyimide for mating with our micro-neurostimulator designs. We will also evaluate the biocompatibility and biostability of these structures, which will be done in part at the CIVR through both in vitro soak-testing experiments and through survival surgeries in Yucatan mini- pig animal models with active and passive devices. Together with our vendors, we will fabricate new generations of high-density ceramic feedthroughs and incorporate these into state-of-the- art 200-channel hermetic titanium packages for our retinal microstimulators that will lead to clinically relevant visual prosthetics. The relationship between the proposed effort and the ongoing patient care mission of the VA is that these improvements are expected to open up new rehabilitative possibilities through more specific, targeted neural stimulation than has previously been possible- especially for the restoration of truly useful vision to blind patients, but also in other areas of medicine such as deep brain or spinal cord stimulation. In sum, it is our hope that the blind population we serve will ultimately benefit from the improved visual acuity that will arise from our ability to create complex, highly biostable retinal neurostimulators; additionally, the channel capacity and efficacy of future wireless implantable prostheses of all types is expected to be improved.